term 1 - chemistry reactions, profiles and rates

Question 1

the number of protons and electrons in an element is the same as?

Answer 1

the element’s atomic number

Question 2

how do you find the number of neutrons an element has?

Answer 2

atomic mass - atomic number

Question 3

(1) all matter is composed of _____, and has ____ and ______?

Answer 3

atoms
mass
volume

Question 4

(3) endothermic reaction?

Answer 4

heat energy is ‘absorbed’ and the temperature lowers

Question 5

(3) exothermic reaction?

Answer 5

heat energy is ‘released’ during the reaction and the temperature increases

Question 6

bonds of reactants have more energy than the products?

Answer 6

exothermic

energy difference is given out as heat

Question 7

bonds of reactants have less energy than the products?

Answer 7

endothermic

extra energy is needed to form the product, which is taken from its surroundings, so the temperature falls

Question 8

(2) signs of a chemical change?

Answer 8

temperature change

colour change

light emmited

fizz/bubbles/gas

precipitate/solid is formed

smell/odour

Question 9

photosynthesis and respiration are _________?

Answer 9

opposites

Question 10

photosynthesis is ___________ reaction?

Answer 10

endothermic

Question 11

respiration is __________ reaction?

Answer 11

exothermic

Question 12

how do you know that a chemical reaction involves oxygen/word equation for an element + oxygen?

Answer 12

you see something burn + the energy is released in the form of heat and light

not every substance reacts with oxygen in the same way

element + oxygen = oxide + energy

Question 13

what happens when hydrogen burns in oxygen?

Answer 13

large amounts of heat are released, which can be dangerous in an uncontrolled environment

Question 14

fuel?

Answer 14

substance that will have a large amount of useful energy quickly once it undergoes a chemical reaction

Question 15

what do many fuels contain?

Answer 15

hydrocarbons

compounds of carbon and hydrogen

Question 16

(4 and 5) combustion?

Answer 16

oxygen + often contains carbon and hydrogen. living things

exothermic reaction that occurs at different rates

produces heat or light energy

Question 17

(4) what is corrosion?

Answer 17

When a metal is attacked by substances around it such as moisture, acids, etc.
eg. rust of iron

Question 18

(4) what type of reaction is corrosion?

Answer 18

process involves oxygen and water therefore it is a form of combustion (non-living)

Question 19

(9) what affect does temperature have on a reaction?

Answer 19

more heat = more speed = more collisions

particles turn heat into kinetic energy

Question 20

(9) what affect does concentration have on a reaction?

Answer 20

more particles in same space = more collisions

Question 21

(9) what affect does catalysts have on a reaction?

Answer 21

reduce activation energy needed for a reaction

less activation energy = more effective collisions = faster rate

Question 22

(9) what affect does surface area have on a reaction?

Answer 22

increase in SA —> more collisions

more collisions = more effective collisions = faster rate

Question 23

(9) activation energy?

Answer 23

minimum amount of energy to start a reaction

Question 24

collision theory?

Answer 24

reactions do not happen unless particles are in contact and able to collide. particles are constantly moving.

Question 25

(11) pH scale?

Answer 25

measure of how acidic or basic (alkaline) something is

Question 26

(11) properties of an acid?

Answer 26

ph of less than 7 taste sour indicator: blue —> red

Question 27

(11) properties of base?

Answer 27

ph of more than 7 taste bitter indicator: red —> blue

Question 28

(12) word equation for combustion?

Answer 28

fuel (butane) + oxygen —> carbon dioxide + water

Question 29

(12) word equation for acids and metals?

Answer 29

metal + acid —> salt + hydrogen

Question 30

(12) word equation for metal carbonate and acids?

Answer 30

metal carbonate + acid —> salt + water + carbon dioxide

Question 31

(12) word equation for precipitation?

Answer 31

two soluble reactants form a soluble product and an insoluble product (precipitate) reactant ab + reactant cd —> product ad + product bc

Question 32

(13) decomposition?

Answer 32

a single compound breaks down into two or more substances reactant ab —> product a + product b

Question 33

(13) neutralisation?

Answer 33

acids neutralise with bases (or vice versa) to become neutral always produces a salt and water

Question 34

(14) test for hydrogen gas?

Answer 34

pop test

Question 35

(14) test for carbon dioxide?

Answer 35

milky limewater

Question 36

(14) test for oxygen gas?

Answer 36

glowing splint

Question 37

why are indicators used in chemical experiments?

Answer 37

to identify chemical conditions

Question 38

hydrocarbon + oxygen?

Answer 38

carbon dioxide + water + energy